dtlib: remove unused variable

This is unused since the very beginning of the module's introduction.
It looks like it was abandoned in favor of the approach where each
token can have only one capturing group.

Signed-off-by: Martí Bolívar <[email protected]>

Author: mbolivar-nordic

scripts/dts/python-devicetree/src/devicetree/dtlib.py

@@ -1939,11 +1939,6 @@ def _err(msg) -> NoReturn:
 # '\c', where c might be a single character or an octal/hex escape.
 _unescape_re = re.compile(br'\\([0-7]{1,3}|x[0-9A-Fa-f]{1,2}|.)')
 
-# #line directive (this is the regex the C tools use)
-_line_re = re.compile(
-    r'^#(?:line)?[ \t]+([0-9]+)[ \t]+"((?:[^\\"]|\\.)*)"(?:[ \t]+[0-9]+)?',
-    re.MULTILINE)
-
 def _init_tokens():
     # Builds a (<token 1>)|(<token 2>)|... regex and returns it. The
     # way this is constructed makes the token's value as an int appear